PURPOSE: To simplify circuit constitution driving a bucket cylinder and a bucket opening-closing cylinder.
CONSTITUTION: A directional control valve 6A for opening and closing a bucket, a directional control valve 7A for a boom and a directional control valve 8 for an arm are arranged on the pump 1 side, and a directional control valve 10 for the arm, a directional control valve 11 for the boom and a directional control valve 12 for the bucket are disposed on the pump 2 side. A connecting path 23 connecting the downstream of the directional control valve 8 for the arm on the most downstream of a changeover valve group on the pump 1 side and above-mentioned directional control valve 12 for the bucket is mounted, and an opening-closing control valve being interlocked with a control lever 21A for the bucket and opening and closing a center bypass on the pump 1 side is installed on an upstream in the vicinity of a fixed throttle 15 arranged in the lowermost flow of the center bypass on the pump 1 side. Changeover valves 35, 36 being interlocked with the lever 21A and holding the directional control valve 8 for the arm at a neutral place and changeover valves 37, 38 holding the directional control valve 11 for the boom at the natural place are set up.
AOYANAGI YUKIO
KATSUKI KIMIO
YASUDA TOMOHIKO
